In order to answer the questions Rakshit first wrote down the electronic configurations of the element `X,Y` and `Z` by using their atomic numbers as follows:
(a) (i) Element `X` has 4 valence electrons in its atom, so it will occur in group `4+10=14` of the modern periodic table.
(ii) Element `Y` has 6 valence electrons in its atom, so it will be found in group `6+10=16` of the modern periodic table.
(iii) Element `Z` has just 1 valence electron in its atom, so it will be in group 1 of the modern periodic table.
(b) An ionic bond is formed between a metal element and a non-metal element. Now, element `Z` of group 1 is a metal and element `Y` of group 16 is a non-metal, therefore, the elements `Z` and `Y` will combine to form ionic bonds (Please note that element `X` of group 14 is also a non-metal carbon but it does not combine with metals to form ionic bonds).
(c) The element `Z` has 1 valence electron, so its valency is 1 (or 1+). Element `Y` has 6 valence electron so its valency will be 2 (or `2-`). Here two `Z^(+)` ions will combine with one `Y^(2-)` ion so that the formula of ionic compound formed will be `Z_(2)Y`.
(d) A covalent bond is formed between two non-metal elements. Here, element `X` of group 14 a non-metal and element `Y` of group 16 is also a non-metal therefore, the elements `X` and `Y` will combine together to form covalent bonds.
(e) The element `X` has 4 valence electrons, so its valency is 4. The element `Y` has 6 valence electrons so its valency is 2. This means that one atom of element `X` will combined with two atoms of element `Y` to form a covalent compound having he formula `XY_(2)`.
(f) The values displayed by Rakshit in answering these questions are (i) Knowledge of modern classification of elements (ii) Understanding of periodic table and chemical bonding and (iii) Problem solving skills.
